This invention generally relates to disposable absorbent articles of the type placed against a wearer's body to receive liquids discharged therefrom, and more particularly relates to disposable catamenial pads and the like. Still more particularly, this invention relates to disposable catamenial pads for use between periods of menstruation in which the outer wrap is a homogeneous sheet of material having a multiplicity of protuberances comprising debossments in the topsheet and backsheet portions of the outer wrap. The physical characteristics of the debossments in the topsheet portion and of the debossments in the backsheet portion are substantially similar to each other.
Disposable absorbent articles of the type placed against a wearer's body to receive liquids discharged therefrom are well-known in the prior art and have many uses. For example, disposable diapers are intended to absorb and contain urine; bandages are intended to absorb and contain blood and other body exudates; catamenial pads are intended to absorb and contain menstrual fluids; while pantiliners are intended primarily to absorb and contain vaginal discharges other than menstrual fluids. In each instance, the disposable absorbent article absorbs and contains a liquid, thereby preventing that liquid from soiling, wetting, or otherwise contaminating the vicinity surrounding the point of liquid discharge.
In general, disposable absorbent articles all have the same basic structure which comprises an absorbent core encased in an outer wrap. Frequently, the prior art outer wraps have a liquid permeable user contacting topsheet and a liquid impermeable backsheet. The materials taught in the prior art for use as topsheets have characteristics which permit liquid to rapidly penetrate their thickness while materials which retard the flow of liquid are suggested for use as backsheets.
Because the topsheet and the backsheet components of the outer wrap require liquid handling characteristics which are different from each other, the prior art absorbent articles typically have topsheets and backsheets which are manufactured from materials having different physical characteristics. For example, U.S. Pat. No. RE 26,151 entitled "Disposable Diaper" which issued to R. C. Duncan et al. on Jan. 31, 1967, teaches a disposable absorbent article having a topsheet which is a hydrophobic paper or non-woven fabric web while the backsheet is a polyethylene web.
There have been numerous patents issued which are directed to improving the characteristics of various materials so that they will function better either as a topsheet or as a backsheet. For example, U.S. Pat. No. 3,929,135 entitled "Absorptive Structure Having Tapered Capillaries" which issued to H. A. Thompson on Dec. 30, 1975, teaches a topsheet of liquid impervious material provided with tapered capillaries. The tapered capillaries are sized so as to promote rapid liquid penetration through the topsheet thereby presenting a dry surface feel to the user. U.S. Pat. No. 3,881,489 entitled "Breathable Liquid Impervious Backsheet For Absorptive Devices" which issued on May 6, 1975 to E. W. Hartwell and U.S. Pat. No. 3,989,867 entitled "Absorptive Devices Having Porous Backsheet" which issued to J. B. Sisson on Nov. 2, 1976, both teach backsheets for absorptive devices which permit the passage of air and vapor but act as a barrier to the passage of liquid.
By using materials having different physical characteristics for the topsheet and backsheet components of the outer wrap, the liquid handling characteristics of each may be optimized. In some manufacturing methods and for some product applications, however, it is desirable to use the same, or substantially the same material for both the topsheet and backsheet components.
In those prior art disposable absorbent articles which utilize a homogeneous outer wrap, a separate liquid barrier is provided. This barrier may take the form of a treatment of a portion of the outer wrap. Alternatively, as taught in U.S. Pat. No. 4,200,103 entitled "Increasing Absorbent Capacity of Sanitary Napkin By Sealing Cover Material To Repellant Barrier" which issued to Black et al. on Apr. 29, 1980, a liquid impervious barrier sheet may be introduced to serve the function of the liquid impervious backsheet.
The disposable absorbent articles of the prior art lack the aspects of the present invention whereby a barrierless disposable absorbent article is provided, comprising a homogeneous sheet of material wrapped around an absorbent core.
It is, therefore, an object of the present invention to provide a barrierless disposable absorbent article having a homogeneous outer wrap.
It is another object of the present invention to provide a barrierless disposable absorbent article having a homogeneous outer wrap in which the debossments in the topsheet portion are substantially similar to the debossments in the backsheet portion.
It is a further object of the present invention to provide a barrierless disposable absorbent article having a homogeneous outer wrap in which the debossments are configured so as to be suitable for use in either the topsheet portion or the backsheet portion of the outer wrap.
These and other objects of the invention will be more readily apparent when considered in reference to the following description and when taken in connection with the accompanying drawings.